We advise that growth of the unwanted hair of the disabled son be eliminated by some means.
If that is not possible, then request a male to remove the unwanted hair. If a male is not available and the unwanted hair is medically harmful, then the mother will be excused for removing the hair. The use of a hair removing cream will be preferred over shaving.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai